A cellular or mobile network can include base stations for communicating with wireless devices located within the network's cells. For example, the base stations can transmit signals to wireless devices via a downlink channel and can receive signals from the wireless devices via an uplink channel.
A Wi-Fi network can include several access points for communicating with close proximity Wi-Fi enabled devices such as laptops and smartphones. For example, a Wi-Fi access point can transmit signals via a Wi-Fi downlink channel to Wi-Fi enabled devices, such as computers or smartphones, and can receive Wi-Fi signals via a Wi-Fi uplink channel.
Broadcast television transmission refers to the transmission of radio frequency television channels within designated frequency bands by a television transmitter. The transmitted signal is captured by a television antenna, and channels are tuned by a television receiver.